What about EC? Are redundant data spread across multiple servers? If not, 
multiple replica would be placed on the same server. I can loose 2 bricks (2 
disks) but what if I'll loose the whole server with both bricks on it? And when 
a server fails, multiple bricks are affected ......... 

----- 

Yes, redundant data spread across multiple servers. In my example I mentioned 6 
different nodes each with one brick. 
Point is that for 4+2 you can loose any 2 bricks. It could be because of node 
failure or brick failure. 
1 - 6 bricks on 6 different nodes - any 2 nodes may go down - EC win 

However if you have only 2 nodes and 3 bricks on each nodes, then yes in this 
case even if one node goes down, ec will fail because that will cause 3 bricks 
down. 
In this case replica 3 would win. 


----- Original Message -----

From: "Gandalf Corvotempesta" <[email protected]> 
To: "Ashish Pandey" <[email protected]> 
Cc: [email protected] 
Sent: Tuesday, August 9, 2016 11:08:12 PM 
Subject: Re: [Gluster-users] Need help to design a data storage 



Il 09 ago 2016 19:20, "Ashish Pandey" < [email protected] > ha scritto: 
> 3 - EC with redundancy 2 that is 4+2 
> The over all storage space you get is 4TB and any 2 bricks can be down at any 
> point of time. So it is as good as replica 3 but providing more space. 

Not really. 
With replica 3 i can set the brick location on different servers so that i can 
loose multiple servers and not only multiple bricks 

What about EC? Are redundant data spread across multiple servers? If not, 
multiple replica would be placed on the same server. I can loose 2 bricks (2 
disks) but what if I'll loose the whole server with both bricks on it? And when 
a server fails, multiple bricks are affected ......... 

replica 3 is like a raid10 with 3 disks in each mirror (3 failed bricks in the 
same replica set=data loss). EC is like raid6 (3 failed bricks in the whole 
cluster=data loss). The first is safer than the latter but has a huge waste of 
space. 
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